1. Field of the Invention
This invention pertains to a torque converter drive unit which couples power from an engine-driven torque converter in a racing vehicle to an output shaft which, when attached to a transmission to allow gear ratio changes and provide a neutral and reverse gear, drives the wheels of the vehicle.
2. Description of the Background Art
In the area of automobile drag racing, it is important to achieve a quick start off the line. One method of achieving a quick start is to hold the vehicle in place with the wheel brakes, operate the vehicle engine at high speed, stall the torque-converter equipped automotive transmission which is coupled to the drive shaft, and then release the wheel brakes. Another method is to adapt a torque converter-equipped automotive transmission to operate in both forward gear and reverse gear at the same time, and to quickly release the reverse gear thus propelling the vehicle forward. Because of the high torque developed by drag racing engines, however, wheel brakes are generally inadequate, and adapted transmissions fatigue quickly or are destroyed after a few uses.
At present, the most widely used device is a passenger-car planetary transmission modified so that both the forward gear and reverse gear can be engaged at the same time for a braking effect. These devices are simply not capable of surviving the stress developed by high torque engines in this application.
Various automotive transmission apparatus are known in the art. For example, Japanese Patent No. 46-35284 issued to Honda Giken KK on Jan. 23, 1967, discloses an apparatus in which a control valve which is opened by the ratio of 1:1 in response to a torque ratio is disposed on the torque converter and the valve is interposed in a pressure oil supply circuit of a hydraulic clutch which is in parallel with the converter characterized in that a second control valve is provided which is opened at a high speed in response to the speed of a transmitting shaft; and the second valve is interposed in said pressure oil supply circuit in series with said control valve so that an oil supply to the clutch is interrupted automatically at the low speed of the transmitting shaft.
British Patent No. 712,290 issued to Svenska Rotor Maskiner Aktiebolag on July 21, 1954, discloses a power transmission comprising a hydraulic torque converter constructed for alternative operation as a single rotation or double rotation converter for transmitting power from a driving member to a driven member, a rotatably mounted reaction member, releasable braking means for holding said reaction member rotationally stationary and to release the same for rotation in either direction, fluid pressure actuated means for engaging said braking means including a control valve and means responsive to predetermined variations in the speed ratio between said driving and driven members for moving said valve to effect engagement or release of said braking means.
British Patent No. 885,553 issued to Clark Equipment Company on Dec. 28, 1964, discloses a power transmission mechanism comprising a hydrodynamic torque converter, a selectively engagable fluid pressure actuated clutch for connecting the torque converter to a load, a fluid distributor, a high pressure passage communicating with an inlet passage in the distributor and with the fluid activated clutch, two low pressure passages, and low and high pressure valves. The apparatus provides a unitary substructure to avoid the complexity of fluid circulation passages in conventional transmissions.
Canadian Patent No. 654,123 issued to Ahlen on Dec. 18, 1962, discloses a power transmission and braking device comprising a hydraulic torque converter having a primary or pump member connected to the driving shaft, a secondary member connected to the driven shaft, a rotatably mounted reaction member, a reversing mechanism connecting said reaction member and said turbine member, means for selectively connecting said pump member and said turbine member for simultaneous rotation at a speed ratio of unity, and control means for selectively engaging said reversing mechanism to drive said reaction member in a direction opposite to that of said turbine and pump members when said turbine and pump members are driven as a unit on one and the same direction to provide a hydraulic braking effect.
U.S. Pat. No. 3,578,120 issued to Hilpert on May 11, 1971, discloses a hydraulically operated friction device, such as a clutch or a brake, which have hydraulic means for varying the amount of clamp up between the interleaved clutch plates, thereby providing a controllable amount of slip between the drive and driven members of the clutch.
U.S. Pat. No. 4,876,922 issued to Koshimo on Oct. 31, 1989, discloses a stepless speed-change transmission for a vehicle. The apparatus prevents power from being transmitted to the driven shaft when the vehicle is at rest, thus eliminating creep and providing smooth power transition when desired.
Various other transmission related apparatus are also shown. For example, U.S. Pat. No. 3,659,690 issued to Kitano et al. on May 2, 1972, discloses a hydraulic control system for a vehicle having a transmission provided with fluid activated clutch means connected to a torque converter and hydraulic brake means for arresting movement of the vehicle. U.S. Pat. No. 3,473,411 issued to Paredes on Oct. 21, 1969, discloses a hydrokinetic torque converter for use in an automotive vehicle drive line. U.S. Pat. No. 4,246,997 issued to Tarumizu on Jan. 27, 1981, discloses an apparatus for allowing a clutch equipped torque converter to slip when an engine is at high idle but keep engaged without slip at low idle. U.S. Pat. No. 4,361,217 issued to Bieber et al. on Nov. 30, 1982, discloses a clutch assembly for a semiautomatic gear transmission. U.S. Pat. No. 4,580,671 issued to Matsuoka et al. on Apr. 8, 1986, discloses a control system for a lock-up torque converter attached to an automobile automatic power transmission.
Although the foregoing patents address some of the various needs of the industry, the devices disclosed in those patents are not capable, even with modification, of instantaneously transferring high levels of mechanical power to driven wheels without risk of failure, a deficiency which the subject invention overcomes. The foregoing patents reflect the state of the art of which the applicant is aware and are tendered with the view toward discharging applicant's acknowledged duty of candor in disclosing information which may be pertinent in the examination of this application. It is respectfully stipulated, however, that none of these patents teach or render obvious, singly or when considered in combination, applicant's claimed invention.